scholarly journals The AGN-Starburst Connection traced by the Nitrogen Abundance

2012 ◽  
Vol 8 (S290) ◽  
pp. 273-274
Author(s):  
Kenta Matsuoka ◽  
Tohru Nagao ◽  
Alessandro Marconi ◽  
Roberto Maiolino ◽  
Yoshiaki Taniguchi
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
Agb Stars ◽  
Line Flux ◽  
Quasar Spectra ◽  
Star Formation Activity ◽  
Nitrogen Abundance

AbstractThe connection between the active galactic nuclei (AGNs) and star formation activity is one of the most important issues in understanding the coevolution of supermassive black holes (SMBHs) and galaxies. In our recent study, by using SDSS quasar spectra we found that the emission-line flux rations involving a nitrogen line correlate with the Eddington ratio. This correlation suggests that the mass accretion in quasars is associated with a post-starburst phase, when AGB stars enrich the interstellar medium with the nitrogen. Moreover, we focused on nitrogen-loud quasars, that have prominent emission lines of the nitrogen, to investigate whether this argument is correct. In this symposium, we present our results regarding the relation between the star formation and feeding to SMBHs traced by the nitrogen abundance.

scholarly journals Constraining photoionization models with a reprojected optical diagnostic diagram

2020 ◽  
Vol 499 (4) ◽  
pp. 5749-5764 ◽  
Author(s):  
Xihan Ji ◽  
Renbin Yan
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Theoretical Models ◽  
Line Ratio ◽  
Star Forming ◽  
Optical Diagnostic ◽  
Diagnostic Diagram ◽  
Upper Limits ◽  
Nitrogen Abundance

ABSTRACT Optical diagnostic diagrams are powerful tools to separate different ionizing sources in galaxies. However, the model-constraining power of the most widely used diagrams is very limited and challenging to visualize. In addition, there have always been classification inconsistencies between diagrams based on different line ratios, and ambiguities between regions purely ionized by active galactic nuclei (AGNs) and composite regions. We present a simple reprojection of the 3D line ratio space composed of [N ii]λ6583/H α, [S ii]λλ6716, 6731/H α, and [O iii]λ5007/H β, which reveals its model-constraining power and removes the ambiguity for the true composite objects. It highlights the discrepancy between many theoretical models and the data loci. With this reprojection, we can put strong constraints on the photoionization models and the secondary nitrogen abundance prescription. We find that a single nitrogen prescription cannot fit both the star-forming locus and AGN locus simultaneously, with the latter requiring higher N/O ratios. The true composite regions stand separately from both models. We can compute the fractional AGN contributions for the composite regions, and define demarcations with specific upper limits on contamination from AGN or star formation. When the discrepancy about nitrogen prescriptions gets resolved in the future, it would also be possible to make robust metallicity measurements for composite regions and AGNs.

scholarly journals Intensity ratios for XDR/PDR identification

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
C.-E. Green ◽  
M. R. Cunningham ◽  
J. A. Green ◽  
J. R. Dawson ◽  
P. A. Jones ◽  
...  
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Active Galactic Nuclei ◽  
Intensity Ratio ◽  
Galactic Nuclei ◽  
Relative Influence ◽  
Calculation Methods ◽  
X Ray ◽  
Ratio Calculation ◽  
Intensity Ratios

AbstractThe intensity ratios of HCO+/HCN and HNC/HCN (1-0) reveal the relative influence of star formation and active galactic nuclei (AGN) or black holes on the circum-nuclear gas of a galaxy, allowing the identification of X-ray dominated regions (XDRs) and Photon-dominated regions (PDRs). It is not always clear in the literature how this intensity ratio calculation has been, or should be performed. This paper discusses ratio calculation methods for interferometric data.

scholarly journals STAR FORMATION RATES FROM [C II] 158 μm AND MID-INFRARED EMISSION LINES FOR STARBURSTS AND ACTIVE GALACTIC NUCLEI

2014 ◽  
Vol 790 (1) ◽  
pp. 15 ◽  
Author(s):  
L. Sargsyan ◽  
A. Samsonyan ◽  
V. Lebouteiller ◽  
D. Weedman ◽  
D. Barry ◽  
...  
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Infrared Emission ◽  
Emission Lines ◽  
Mid Infrared

scholarly journals Star formation in accretion discs and SMBH growth

2020 ◽  
Vol 493 (3) ◽  
pp. 3732-3743 ◽  
Author(s):  
Alexander J Dittmann ◽  
M Coleman Miller
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Active Galactic Nuclei ◽  
Accretion Rate ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Compact Objects ◽  
Accretion Discs ◽  
Massive Black Holes ◽  
Gas Accretion

ABSTRACT Accretion discs around active galactic nuclei (AGNs) are potentially unstable to star formation at large radii. We note that when the compact objects formed from some of these stars spiral into the central supermassive black hole (SMBH), there is no radiative feedback and therefore the accretion rate is not limited by radiation forces. Using a set of accretion disc models, we calculate the accretion rate on to the central SMBH in both gas and compact objects. We find that the time-scale for an SMBH to double in mass can decrease by factors ranging from ∼0.7 to as low as ∼0.1 in extreme cases, compared to gas accretion alone. Our results suggest that the formation of extremely massive black holes at high redshift may occur without prolonged super-Eddington gas accretion or very massive seed black holes. We comment on potential observational signatures as well as implications for other observations of AGNs.

scholarly journals A search of new samples of active galactic nuclei with low-mass black holes from SDSS

2014 ◽  
Vol 10 (S312) ◽  
pp. 75-76
Author(s):  
H. Liu ◽  
W. Yuan ◽  
H. Zhou ◽  
X.-B. Dong
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
Line Width ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
Broad Line ◽  
Galaxy Sample ◽  
Low Mass ◽  
The Masses ◽  
Larger Sample

AbstractWe report on the progress of our on-going work to search for low-mass black holes (LMBHs) in active galactic nuclei. The masses of black holes are estimated using the broad line width and luminosity obtained from one-epoch optical spectra. As the first step, we fitted the spectra of 1263 objects in the quasar catalog of the SDSS DR10 and obtained accurate measurement of the emission lines. Two AGNs are found to have MBH ~ 106 M⊙. The next step is to analyze the spectra of the DR10 galaxy sample, from which a much larger sample of low-mass AGNs is expected to be obtained.

Role of environment on AGN activity

2019 ◽  
Vol 15 (S356) ◽  
pp. 171-171
Author(s):  
Amirnezam Amiri
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galaxy Clusters ◽  
Galactic Nuclei ◽  
Stellar Mass ◽  
Local Universe ◽  
Nuclear Activity ◽  
Star Forming ◽  
Star Formation Activity

AbstractMotivated by the apparently conflicting results reported in the literature on the effect of environment on nuclear activity, we have carried out a new analysis by comparing the fraction of galaxies hosting active galactic nuclei (AGNs) in the most overdense regions (rich galaxy clusters) and the most underdense ones (voids) in the local universe. Exploiting the classical BPT diagnostics, we have extracted volume limited samples of star forming and AGN galaxies. We find that, at variance with star-forming galaxies, AGN galaxies have similar distributions of specific star formation rates and of galactic ages (as indicated by the Dn4000 parameter) both in clusters and in voids. In both environments galaxies hosting AGNs are generally old, with low star formation activity. The AGN fraction increases faster with stellar mass in clusters than in voids, especially above 1010.2 M⊙. Our results indicate that, in the local universe, the nuclear activity correlates with stellar mass and galaxy morphology and is weakly, if at all, affected by the local galaxy density.

scholarly journals The Mid-Infrared Spectral Properties of Starburst Galaxies and Active Galactic Nuclei

1999 ◽  
Vol 194 ◽  
pp. 54-59
Author(s):  
O. Laurent ◽  
I.F. Mirabel
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Infrared Spectra ◽  
Diagnostic Tool ◽  
Active Galactic Nucleus ◽  
Spectral Properties ◽  
Galactic Nuclei ◽  
Mid Infrared ◽  
Star Formation Activity ◽  
Infrared Spectral

We present a new diagnostic tool based on mid-infrared spectra (5–16μm) for distinguishing the emission triggered by the active galactic nucleus (AGN) and by the star formation activity. We show that the AGN spectra, contrary to the starburst spectra, present an important continuum below 9μm and an absence of Unidentified Infrared Bands (UIBs).

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